Bee communities and pollination services in adjacent crop fields following flower removal in an invasive forest shrub

Abstract

Citation: Cunningham-Minnick, M. J., V. E. Peters, and T. O. Crist. 2020. Bee communities and pollination services in adjacent crop fields following flower removal in an invasive forest shrub. Ecological Applications 30(4):Abstract. The habitat boundaries between crops and seminatural areas influence bee movements and pollination services to crops. Edges also provide favorable conditions for invasive plants, which may usurp pollinators and reduce visitation to native or crop plants. Alternatively, floral displays of alien plants may facilitate, or increase, the pollination success of adjacent plants by attracting more pollinators to the area. Therefore, pollination services of bees from seminatural habitats to crop areas should vary with the presence of invasive floral resources and distance from habitat edges. To test the hypothesis that floral resources of invasive forest shrubs affect the bee community and pollination services in adjacent crop fields, we conducted a 2-yr field experiment along forest-crop edges at five isolated forest remnants. We removed flower buds from a dominant invasive shrub, Lonicera maackii (Amur honeysuckle), along forest-crop edges and paired removals with controls of intact flowers. The bee community, their pollination services, and flower visitation rates were quantified along a 200-m gradient into an adjacent crop field using pan traps and sentinel cucumber plants. Impacts to the bee community were dependent of bee functional traits. Larger bees visited fewer sentinel cucumber flowers in flower removal plots, which corresponded with decreased cucumber pollination compared to plots with honeysuckle flowers at distances >100 m from forest edges. Small-bodied and weaker flying bees visited sentinel plants more frequently closer to the forest edge and increased pollination services to cucumber at distances <100 m from L. maackii shrubs in flower removal plots. After 2 yr, bee abundance and species richness increased within flower removal plots across all distances. High functional diversity of the bee community increased pollination services to sentinel plants and increased cucumber production within 200 m from forest remnants. Our findings suggest that dense floral resources of invasive shrubs suppressed forest-edge bee communities and their pollination services, but also attracted large-bodied generalist bees, which were effective pollinators. This study helps explain how life histories and functional attributes of bees can predict either facilitation or suppression of pollination services to crop or native plants in response to invasive floral resources.

Effect of Landscape Composition and Invasive Plants on Pollination Networks of Smallholder Orchards in Northeastern Thailand

“…Studies of plant–pollinator networks can support conservation strategies, and the coexistence of pollinators and plants within natural and agricultural systems [ 19 , 54 ]. Both agricultural diversity and the appropriate arrangement for invasive plants are associated with increasing pollinator dependence which could support pollination networks and provide resources for generalist pollinators that facilitate the pollination of native plants [ 55 , 56 , 57 ]. We found evidence not only that the richness of local vegetation influences the pollinator diversity, but also that invasive flowering plants can actually increase insect diversity.…”

“…As flowering period of many crop species are limited, and other floral resources are needed to sustain pollinators outside these peak flowering periods. Once invasive plant species expand their ranges, they may alter phenology and can actually help maintain pollinators when few floral resources are available [ 57 , 58 , 59 ]. We suggest further studies should investigate the effective competition for pollination between the invasive plant P. clematidea and native plants.…”

Land-Use Change in a Mexican Dry Forest Promotes Species Turnover and Increases Nestedness in Plant-Hummingbird Networks: Are Exotic Plants Taking Over?

“…Although exotic plants represent important food resources for hummingbirds in disturbed areas, they could also have negative effects. They may usurp pollinators and reduce visitation to nearby native plants (Bartomeus et al., 2008; Cunningham-Minnick et al., 2020). Thus, a different experimental approach will be helpful to elucidate if hummingbirds (or other pollinators) do prefer exotics over native plant species.…”

“…Likewise, disturbed habitats may act as ecological traps for hummingbirds if, for example, they prefer to nest at sites where egg and/or nestling survivorship shrinks due to higher exposure to predators (Battin, 2004). Alternatively, floral displays of exotic plants may facilitate or increase the pollination success in adjacent plants by attracting more pollinators to the area (Bartomeus et al., 2008; Cunningham-Minnick et al., 2020). Given this, patches of disturbed habitat may enhance landscape heterogeneity, providing complementary resources to the native remnants (Fonturbel et al., 2017) or provide complementary resources when they are scarce at the conserved areas (Bartomeus et al., 2008).…”

Spillover effects from invasive Acacia alter the plant–pollinator networks and seed production of native plants

“…Spillover effects of bordering cropland upon native plants are well described, causing, for example, pollinator dilution [16,17] or increasing numbers of agriculturally subsidized natural enemies [18][19][20]. However, there is a dearth of such literature regarding spillover effects of invasive plants, and both agricultural and invasive contexts lack community-level plant-pollinator network studies ( [21], but see [22]). Thus, do pollinators visiting dense stands of flowering invasive plants spill over into native habitats and impact adjacent, uninvaded plant-pollinator communities, i.e.…”